2009-05-09

Back in the days on "The Talk of the Town" 930 CJCA (when it was talk radio, not Christian programming), his morning highlight and possibly the only reason my father didn't commit suicide in the 1980s recession was "The Bill and Bill Show" with Bill Matheson (the infamous weather guy) and Bill Jackson.

Amoungst their many topics, the most polarizing (heh heh) of all had to be the endless discussions of "do the northern lights make noise". At least twice a month the topic would come up and you'd get insistant calls from people who'd live in the north their entire lives who insisted that they had never once heard the northern lights make noise, followed by falls from more people who had lived in the north their entire lives who insisted that they had always heard them make noise. Then somebody would call up and say they were a scientist and explain briefly why the northern lights had to make noise, followed by another phone call from another scientist who patiently explained how the northern lights couldn't possibly make noise.

Well, Wikipedia doesn't even mention the controversy, but does link to this page:

The main results of the thesis

The analysis shows statistically significant correlation between the sound power fluctuation and the geomagnetic activity.

The cross-correlations were performed at one-third octave bands with different delay values.

The delays between magnetic field activity and sound power fluctuation at the highest correlation values speak for a sound source relatively close to the measuring place (ground level). Thus the possible audio range sound source (infrasounds excluded) is not located at the aurora light source, 80-100 km above the ground level, but relatively close to the ground.

The same audio data revealed a clear correlation peak at the upper infrasound range (<20Hz) with a delay corresponding to the sound wave traveling-delay from the level of the aurora light source to the ground (this outcome confirms a known result published earlier).

The possible physical mechanisms behind these sound effects are not yet known.

The simultaneously measured local electric field signals (a VLF antenna 20m from the microphone) indicated very low correlation with the measured sound signals (at zero delay) which means that the local electric field cannot be the cause of the acoustic signals detected.

The acoustic measurements were done with a highly sensitive, low noise, measuring microphone (B&K) which is carefully shielded against ambient electric and magnetic field disturbances.

So there you have it citizens: the aurora borealis do indeed make noise, and 1/2 of the callers to the Bill & Bill Show were idiots. (This probably isn't a surprising statistic)